Spring formation



- NOV. 21, 1944. w o BENNETT, JR 2,363,113 4 SPRING FORMATION Filed Dec. 15, 1941 Drprllrllll llll u" an.

5 E E INVEN W L/Q kill/AM Q Bf/V/Vf (fl? Patented Nov. 21, 1944 NT OFFICE f 1 This invention relates to. springs andhas pare ticular reference tosprings formedin quantity with dimensional uniformity and the method of producing such springs. I

An .objectof this invention. isto provide, simply and inexpensively. springs of dimensionalr uni formity in quantity. I I

Another object is to simultaneously form a quantityof'substantially flat springs of uniform. I

andIequ-al dimensions. n I

Another object is toprovide a method'of forming springs including the steps of winding a :rela- 'tively. long section ofrmaterial about a. holderand severing eachturn of, the winding. II

.Another object is to provide a method of. formsv ing; substantially fiat springs. including thelsteps' of winding a relatively long and narrowfiat spring 3 sufficient.

about a holder having at least; one substantially I flatsurface, heat. treating thegholder and spring I thereon and thereafter severing at leasta portion of the flat surface overlying sectionof each tum of the winding.

Other and further objects will be. clearly ape. parent from .the following specification andfrom 1 I I I I I was thedrawing. I I II .Referringto thedrawing: II I Fig.1 illustrates auholder and spring wound thereon,'as embodied in this. invention;

Fig. II is an elevation. taken onlineIL-II of Fig. I; i i i @Fig. III'is a section taken on line III-II]; of

F -I; '1 i u Fig. IV is a view similar .to Pig. in, showing the. wire contour group of spring wound holders preparatory to :the

spring'wound.holder-.ofzthis. invention, after heat when under compression as in i s. V, VI VII, j I

. Fig. V is an illustration of the stacking: of a treatment and preparatory to cutting the spring into short lengths; and

Fig. VII is an illustration of the operation of p cutting the spring to length, showing one cut as completed.

This invention is particularly directed to springs nd the method of forming them wherein the unprocessed spring is in the form of a coil of relatively fiat, long and narrow material, and the finished springs are relatively short, flat. uncurved II and uniform with each other inparticular with respect to length dimension. Although many var.- iations of the contour. shape and dimension of the finished springs as well as the method of mak I ing them and their uses are readlly possible, for

the purposes of illustration of thel invention, the

following description will. deal. with relatively short,-fiat, and uncurved springs.

' The finished spring isIa flatpiece of'wire 'ap-. proximately .003" x .020x 1.00" and when pros ducing these in quantity it has heretofore been diflicult tokeep Within the alloWableDOiB." tolerance in length. The "present method overcomes the difficulties heretofore presentedtand produces 10 springs of exactlength in lots of 59,000. This, of

I course, couldbe' varied with the size and quantity this invention such who may be woundintight spiral like: contour about. steel strips whose di mensions are approximately 10'. x flg'." x.;l".* From such a. winding 11.000 1". long straight secs tionsof the spring may be'obtained. I It is to be understood, however. that this .vention is not limited to wiresor strips of smalldimension. I I

The process briefly comprises stackingand heat treating a group of such. spring wound :steel holder stripsiunder .compressionon the II" sides thereof, and thereafter clamping each holderstrip with the heat treated wire thereon, on .the l sides and. grinding oifxthose parts ofthe. spring winding which form the end sections, or those which; at least in part.;over1ie the accent the holding strips. I I I I Fig. III illustrates a coil of thewire i wound on the holder Zandshows the coil as itappears when not under compression... and Fig. IV illustrates the difference in contour of the spring under compression as in Figs. V, VI, and VII, and shows the flat portions 3, which, when out off, form the finished short straight springs.

The spring I is first wound about the holder! in a tight spiral like contour. The width dimension of the spring being only .020", .the pitch of the spiral is minute, and the uniformity of length of the finished shortsprings is not affected thereb I I I Having wound the long springs I about the holders 2, a group of these spring wound holders are stacked on each other as shown in Fig. V and clamped between end plates 4 and held by wire windings 5 or other suitable holding means.

This clamping action on the wire I flattens it against the holder 2 as at 3, Fig, IV, through the action of compressors 3 and extends the end loops as at 6, Fig. IV.

The stack of spring Wound holders is then heat treated to harden and set the spring I to its compressed form as shown in Fig. .IV.

Subsequent to this heat treatment, each of the spring wound holders is clamped between end plates 1 having aligning dowels 8 extending through dowel openings 9 in the holders 2, and this assembly is mounted in a chuck In of a grinding machine in such a manner as to provide access to the end loops 6 for a grinding wheel I I.

The end loops 6 are then ground off on both sides of the holder 2 flush with the edges of the holder 2 and clamps I and I0, Accuracy in the length dimension of the finished springs may, in

some instances, be more easily obtained if the end loops 6 are so ground off as to also grind away a part of the edge of the holder 2, to a depth of the order of .O005'f.

Upon removal from the clamps a group of substantially fiat, hardened, short springs of uniform dimension are obtained, representing the straight portions 3, Fig. IV, of the wound wire I.

It is to beunderstood that many variations in dimension, winding, stacking and the like may be used if desired, as for instance the stack of holders of Fig. V may be doweled for position as is the holder of Fig. VI, or the holders may be clamped and heat treated singly or clamped and ground in groups, as is desirable or convenient to suit particular conditions, such as furnace sizeor grinding machine dimension or capacity.

It is to be understood that wire or other suitable material of circular, elliptical, or other cross section may readily be wound about a holder and severed instead of the flat spring used herein as an illustration of the invention.

Also the finished'form of the relatively short, cut out pieces of the long spring may be other than straight in their length dimension. They may be, for example, semi-circular, part of an ellipse, or other desired form providing that the holder and clamping members are formed to the desired finished contour of the springs.

The method of this invention accordingly provides comparatively simple, inexpensive and quick means of forming short flat springs in large quantities and with sufiicient uniformity of dimension as to be readily duplicable in precision devices. l

What I claim is:

'1. A method of forming a plurality of straight spring strips of substantially exact uniformity, consisting in providing a holder having a fiat face conforming in width to the length of the desired spring strips, winding a length of material on said holder to cause the material to conform to the flat surface of the holder, clamping the material on the holder to fix the material relative thereto, heat treating the material and holder while in their relatively fixed relation, and severing the winding beyond the flat face of the holder to leave a series of independent spring strips in accurate conformation with the one side of the holder and of exact uniformity in physical characteristics.

2. A method of simultaneously forming a'plurality of independent spring strips of exactly uniform characteristics, consisting in providing a holder having opposite fiat faces conforming in width to the length of the desired spring strips, windingsaid length of material on a holder to cause the material to conform to the fiat surfaces of the holder, clamping the material with respect to the holder, subjecting the holder and clamped material to heat treatment and removing the portions of the material beyond the fiat faces of the holder, to thereby have a series of fiat spring strips exactly uniform in length. ,1

3'. A method of forming a series of flat sprin strips of exact conformity in size and spring function, consisting in rigidly confining an indefinite length of spring material to present and maintain throughout the indefinite length of material, flat portions of the desired spring'strip length and portions connecting the flat portions in successive order, heat treating the formed indefinite length while rigidly confined in the defined formation, and cutting away those portions of the formed length which connectthe flat portions to thereby 7 leave the flat portions as independent spring strips of exact uniformity.

"4. A method of simultaneously forming a plurality of spring strips of exact relative uniformity, consistingin winding a strip of material of indefinite length on and in conformitywitha holder formed to present opposing flat sides of the desired length of the spring, rigidly maintaining the Wound relation of the strip and holder, heat treating the strip while rigidly held in conformity with the holder and cutting away thoseportionsof the strip beyond its flat sides while maintaining the rigid conformity of the strip and holder, to thereby leave a plurality of flat spring" strips of relative exact physicaluniformity, Q

5. A method of simultaneously formin a plurality of identical spring strips consisting in wrapping a flat wire about a holder to form a-s'eries of short straight length and a series of alternate connecting curved portions,'maintainin'g theshort straight lengths in close relation'to an'd in exact conformity with the holder, heat treating said wire and holder and removing said curved portions to leave aplurality of identical short straight spring lengths.

'IWILLIAM OGLE BENNETT, Ja; 

